Seminar Series Abstract

Ecology of Flatheaded Borers: Implications for Successful Management
in the Nursery and Landscape

Jason B. Oliver¹, Donna C. Fare², Nadeer N. Youssef¹, Sue Scholl², Mark A. Halcomb³, Michael E. Reding⁴, and James J. Moyseenko⁴

¹Tennessee State University, Institute of Agricultural & Environmental Research, Otis L. Floyd Nursery
Research Center, McMinnville, TN; ²USDA-ARS National Arboretum, Nursery Res. Center, McMinnville,
TN; ³University of Tennessee, Institute of Agriculture, McMinnville, TN; ⁴USDA-ARS Horticultural Insects
Res. Laboratory, Wooster, OH

Institute of Agricultural and Environmental Research Seminar Series
Tennessee State University, Nashville, TN
February 22, 2006

A diverse group of insects representing multiple orders, families, genera, and species employ wood-boring as a life history strategy.  A number of these wood-boring insects are important pests of nursery crops and landscape trees.  The objectives of these studies were to 1) determine the importance of wood-boring insects in middle Tennessee nursery and landscape settings and identify key borer groups, 2) gather basic biology data on key borers to facilitate management, and 3) identify effective insecticide treatments for problem wood-borers.  To accomplish objective 1, a series of nursery and landscape surveys were conducted on young trees (generally < 8 cm caliper) to evaluate borer incidence and identify key borer groups.  The survey results indicate borers are important pests depending on tree species with damage ranging from 0 to 55% in landscape settings and 0 to 26% in nursery settings.  Tree species with the greatest frequency of damage were typically those with a 'thin-barked' nature like ash, cherry, crabapple, dogwood, maple, and redbud, while trees with ‘thicker-bark’ like oak had minimal damage.  Overall, borer management appeared to be better in nursery than landscape settings.  Flatheaded borers were the dominant borer group attacking nursery and landscape trees with the exception of ash, which had significant clearwing borer damage.  Roundheaded borer damage was rarely detected in nursery and landscape surveys.  Chrysobothris spp. were the predominant flatheaded borers reared from nursery stock, but other species included Actenodes acornis, Acmaeodera pulchella, Acmaeodera tubulus, and Ptosima gibbicollis.  All species were reared from maple, with the exception of P. gibbicollis, which is found primarily on redbud.  Under objective 2, basic biology data was gathered on flatheaded borers during surveys because these borers were the most important wood-boring group.  Data collected included how borers attacked nursery blocks using a global positioning system, where attacks occurred on the tree trunk, trapping methods to monitor flatheaded borers, and the diurnal timing of adult flight activity.  Results indicate borer attacks on tree blocks are random to slightly aggregate.  Flatheaded attacks on individual tree trunks were predominantly below 20 cm in height and on the southwestern side.  Trapping studies determined that sticky traps with a reflectance in the visible violet range of the electromagnetic spectrum were the most attractive to flatheaded borer adults and two compounds were identified as possible olfactory attractants for Chrysobothris spp.  Adult flatheaded borer flight activity as indicated by traps occurred exclusively during daylight hours.  Lastly, under objective 3, we determined that systemic soil-applied neonicitinoid compounds like Allectus^TM (bifenthrin + imidacloprid), Discus^TM (imidacloprid + cyfluthrin), Flagship^TM 25WG (thiamethoxam), and Marathon^Ò 60WP (imidacloprid) were effective treatments for preventing flatheaded borer damage in nurseries.  An experimental insecticide tablet with imidacloprid (Merit FXT) was moderately effective, but was probably used too late in the season for optimal control.  A Dursban 4E trunk spray was an effective flatheaded borer treatment when applied in mid-May and late June in accordance with current extension recommendations.

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